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authorAndreas Steinmetz <ast@domdv.de>2005-07-23 07:42:04 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2005-07-26 18:30:51 -0400
commit18586e721636527cb5177467fb17e2350615978a (patch)
tree96d34b10d000fa8b1df16ae8f4c73761013371b5
parentfc00a6274b786f6863b32c79ff6f92aa0960b789 (diff)
[PATCH] Fix RLIMIT_RTPRIO breakage
RLIMIT_RTPRIO is supposed to grant non privileged users the right to use SCHED_FIFO/SCHED_RR scheduling policies with priorites bounded by the RLIMIT_RTPRIO value via sched_setscheduler(). This is usually used by audio users. Unfortunately this is broken in 2.6.13rc3 as you can see in the excerpt from sched_setscheduler below: /* * Allow unprivileged RT tasks to decrease priority: */ if (!capable(CAP_SYS_NICE)) { /* can't change policy */ if (policy != p->policy) return -EPERM; After the above unconditional test which causes sched_setscheduler to fail with no regard to the RLIMIT_RTPRIO value the following check is made: /* can't increase priority */ if (policy != SCHED_NORMAL && param->sched_priority > p->rt_priority && param->sched_priority > p->signal->rlim[RLIMIT_RTPRIO].rlim_cur) return -EPERM; Thus I do believe that the RLIMIT_RTPRIO value must be taken into account for the policy check, especially as the RLIMIT_RTPRIO limit is of no use without this change. The attached patch fixes this problem. Signed-off-by: Andreas Steinmetz <ast@domdv.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--kernel/sched.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 4107db0dc091..a5fb654ea590 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3528,7 +3528,8 @@ recheck:
3528 */ 3528 */
3529 if (!capable(CAP_SYS_NICE)) { 3529 if (!capable(CAP_SYS_NICE)) {
3530 /* can't change policy */ 3530 /* can't change policy */
3531 if (policy != p->policy) 3531 if (policy != p->policy &&
3532 !p->signal->rlim[RLIMIT_RTPRIO].rlim_cur)
3532 return -EPERM; 3533 return -EPERM;
3533 /* can't increase priority */ 3534 /* can't increase priority */
3534 if (policy != SCHED_NORMAL && 3535 if (policy != SCHED_NORMAL &&